A detector of this type has already been described in Document FR-A-2 617 965 which shows the implementation of an acoustic waveguide mounted on the side wall of a receptacle containing a liquid. However, the detector described in the above-mentioned document comprises a waveguide which is fixed in conventional manner on the side wall of the receptacle e.g. by means of a clamp, a sleeve, or a nut directly engaging the side wall of the waveguide. Insofar as the acoustic waveguide is itself made in such a manner as to be highly sensitive, the presence of fixing elements that co-operate directly with the surface of the waveguide may interfere to a greater or lesser extent with the transmission of acoustic waves, consequently having an effect on detection quality.
The present invention seeks particularly to remedy the above-mentioned drawbacks and to provide a detector which is highly sensitive to contact with liquid while remaining insensitive to mechanical forces that may be transmitted by the detector support.